1. Field of the Invention
This invention relates to container-closure assemblies wherein the threads of the closure are provided with teeth to resist the backing off of the closure once the closure is properly screwed onto the finish of the container.
2. Description of Related Art including Information Disclosed under .sctn..sctn.1.97 to 1.99
Especially in the assembly in which a closure mounts a trigger pump on the top of a container, it is desirable to preclude the inadvertent unscrewing of the closure. In the filling, transport, storage, sale and use of a container having a trigger pump it is relatively easy for the trigger pump to be knocked in a way that tends to unscrew the closure off the container.
Attempts have been made in the past to avoid such inadvertent loosening of the container closure. An example is shown in the U.S. Pat. No. 4,345,691 which issued Aug. 24, 1982 to James E. Burke wherein the finish of the bottle just under the threads is formed with ratchet teeth and the closure is formed on a downward skirt with reverse ratchet teeth below the threads. When the closure is screwed onto the finish, the ratchet teeth engage, snapping successively as the closure is tightened to firmly hold the trigger pump in position.
In addition, there have been other attempts to form means in the molding of the finish or the closure to assure that once tightened, the closure will be difficult to unscrew off of the top of the container. An example is shown in the Baugh patent 3,682,345 wherein the resilient plastic of the finish or of the cap may be formed adjacent the threads with depending triangularly shaped projections which cause the cold flow of the contiguous surface to indent and create a locking effect. Other examples of deforming the threads of the closure cap or the finish of the container are disclosed in the following patents:
2,035,972 Issued Jun. 19, 1980 to Sendel et al PA0 3,376,991 Apr. 9, 1968 Deaver PA0 3,445,022 May 20, 1969 Cilluffo PA0 3,741,421 Jun. 26, 1973 Wittwer PA0 3,888,376 Jun. 10, 1975 Cooke PA0 3,952,899 Apr. 27, 1976 Cooke PA0 3,963,139 Jun. 15, 1976 Gach PA0 3,979,001 Sep. 7, 1976 Bogert PA0 4,007,850 Feb. 15, 1977 Beaugrand PA0 4,053,077 Oct. 11, 1977 DeFelice PA0 4,084,716 Apr. 18, 1978 Bogert PA0 4,139,112 Feb. 13, 1979 Cooke PA0 4,461,394 Jul. 24, 1984 Sendel et al
The deformation of the screw threads on the cap has been difficult to achieve. Often the deformation has been made while the threads are still unset and after they have been screwed off the core of the mold.